Twistraintronics in Square Moire Superlattices of Stacked Graphene Layers

TL;DR

This study demonstrates how controlled strain in stacked graphene creates square moire patterns, leading to novel correlated electronic states, expanding the possibilities of twistraintronics in moire heterostructures.

Contribution

First observation of strain-controlled square moire patterns in graphene, enabling new electronic states through twist and strain engineering.

Findings

Reversible transition from trigonal to square moire order.

Detection of narrow bands with split Van Hove singularities.

Continuum model reproduces experimental features.

Abstract

We report the first observation of controlled, strain-induced square moire patterns in stacked graphene. By selectively displacing native wrinkles, we drive a reversible transition from the usual trigonal to square moire order. Scanning tunneling microscopy reveals elliptically shaped AA domains, while spectroscopy shows strong electronic correlation in the form of narrow bands with split Van Hove singularities near the Fermi level. A continuum model with electrostatic interactions reproduces these features under the specific twist-strain combination that minimizes elastic energy. This work demonstrates that the combination of twist and strain, or twistraintronics, enables the realization of highly correlated electronic states in moire heterostructures with geometries that were previously inaccessible.